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Non-centrosymmetric material systems can generate spontaneous photocurrent without a p-n junction under uniform illumination, which is known as the bulk photovoltaic effect (BPVE). It has garnered significant attention for its application potential in the fields of energy harvesting and photoelectric detection. In this study, we report the BPVE observed in two-dimensional ferroelectric α-In2Se3 multilayer flakes. The reversal in spontaneous photocurrent polarity is observed and associated with the out-of-plane ferroelectric polarization direction. The spontaneous photocurrent originating from the shift current is also polarization-sensitive. The amplitude of spontaneous photocurrent is further increased by one order of magnitude through vacuum annealing. Our results provide a further application potential for new-generation photodetectors based on BPVE with low power consumption and multi-dimensional optoelectronic detection. [ABSTRACT FROM AUTHOR]

Non-centrosymmetric material systems can generate spontaneous photocurrent without a p-n junction under uniform illumination, which is known as the bulk photovoltaic effect (BPVE). It has garnered significant attention for its application potential in the fields of energy harvesting and photoelectric detection. In this study, we report the BPVE observed in two-dimensional ferroelectric α-In2Se3 multilayer flakes. The reversal in spontaneous photocurrent polarity is observed and associated with the out-of-plane ferroelectric polarization direction. The spontaneous photocurrent originating from the shift current is also polarization-sensitive. The amplitude of spontaneous photocurrent is further increased by one order of magnitude through vacuum annealing. Our results provide a further application potential for new-generation photodetectors based on BPVE with low power consumption and multi-dimensional optoelectronic detection. [ABSTRACT FROM AUTHOR]

p-type semiconductors are significant for integrated nanoelectronics. Tellurium (Te), a mono-elemental material, is a p-type semiconductor with high mobility. Its outstanding performance renders it widely applicable in the fields of electronics and optoelectronics. However, the wafer-scale fabrication of Te thin films is challenging. In this study, we reported an ion-bean sputtered Te thin film and investigated the effects of annealing temperatures. Annealing-induced crystallization kinetics were assessed through Raman spectroscopy, x-ray diffraction, and atomic force microscopy. After annealing, the film's conductivity increased from 10−5 to 10−4 S and mobility from 18 to 53 cm2 V−1 s−1. Dual AC resonance tracking switching spectroscopy piezoelectric force microscopy is used to investigate piezo/ferroelectric properties. The coercive voltages are −2 and 4 V respectively, and the effective piezoelectric coefficient (d33) is 40 pm/V. Butterfly and phase-switching loops demonstrate its possible ferroelectricity. The Te thin film has potential applications in optoelectronics, nonvolatile memory devices, and neuromorphic computation. [ABSTRACT FROM AUTHOR]

2D materials are considered as potential candidates for the next generation of optoelectronic materials. However, their optical absorption is typically weak due to thickness limitations, greatly restricting the photodetection capabilities of devices. To enhance the photoelectric gain of 2D materials or devices and improve detection sensitivity, various modulation methods such as strain, electric field, and magnetic field are commonly introduced. Among them, surface acoustic wave (SAW) represents a unique and effective modulation approach. In this study, photodetectors are fabricated based on few‐layer MoS2 on a SAW delay line on a LiTaO3 substrate. The interaction between SAW and MoS2 successfully manipulates the optoelectronic performance of the MoS2‐based devices. Under the influence of SAW, the dark current of the devices is significantly reduced by more than two orders of magnitude, while the photocurrent remains almost unchanged, resulting in excellent photoresponse performance. The devices provide a promising pathway for high‐performance optoelectronic applications and reveal a new possibility for acoustic devices in optoelectronics. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) layered materials have received significant attention owing to their unique crystal structures as well as outstanding optical and electric properties in photoelectric detection. However, most 2D materials are very sensitive to the environment. Adsorbates and traps introduced during the preparation process have a negative effect on the performance of devices based on these materials. Here, we focus on a molybdenum disulfide (MoS2) phototransistor gated by ferroelectrics, and insert a hexagonal boron nitride (h-BN) layer between MoS2 and the ferroelectric film to improve the interface. To clarify the role of h-BN in this device, two parallel devices are prepared on the same MoS2 flake. One device is covered with h-BN, while the other is in direct contact with the ferroelectric film. The electronic and optoelectronic properties of these two devices are then measured and compared. Experimental results reveal that, compared to device without h-BN, the MoS2 phototransistor with h-BN exhibits higher carrier mobility (average value: 85 cm2·V−1·s−1 and highest value: 185 cm2·V−1·s−1), larger responsivity (85 A·W−1), and larger detectivity (1.76 × 1013 Jones). Thus, this strategy is significant for the interface engineering and performance improvement of devices based on 2D materials. [ABSTRACT FROM AUTHOR]

The two-dimensional layered material CuInP 2 S 6 (CIPS) has attracted significant research attention due to its nontrivial physical properties, including room-temperature ferroelectricity at the ultrathin limit and substantial ionic conductivity. Despite many efforts to control its ionic conductance and develop electronic devices, such as memristors, improving the stability of these devices remains a challenge. This work presents a highly stable threshold-switching device based on the Cu/CIPS/graphene heterostructure, achieved after a comprehensive investigation of the activation of Cu's ionic conductivity. The device exhibits exceptional threshold-switching performance, including good cycling endurance, a high on/off ratio of up to 10 4 , low operation voltages, and an ultrasmall subthreshold swing of less than 1.8 mV/decade for the resistance-switching process. Through temperature-dependent electrical and Raman spectroscopy measurements, the stable resistive-switching mechanism is interpreted with a drifting and diffusion model of Cu ions under the electric field, rather than the conventional conducting filament mechanism. These results make the layered ferroionic CIPS material a promising candidate for information storage devices, demonstrating a compelling approach to achieving high-performance threshold-switching memristor devices.

Flexible optoelectronic devices have numerous applications in personal wearable devices, bionic detectors, and other systems. There is an urgent need for functional materials with appealing electrical and optoelectronic properties, stretchable electrodes with outstanding mechanical flexibility, and gate medium with flexibility and low power consumption. Two-dimensional transition metal dichalcogenides (TMDCs), a novel kind of widely studied optoelectrical material, have good flexibility for their ultrathin nature. P(VDF-TrFE) is a kind of organic material with good flexibility which has been proved to be a well-performing ferroelectric gate material for photodetectors. Herein, we directly fabricated a well-performing photodetector based on ReS 2 and P(VDF-TrFE) on a flexible substrate. The device achieved a high responsivity of 11.3 A W -1 and a high detectivity of 1.7 × 10 10 Jones from visible to near-infrared. Moreover, with strain modulation, the device's responsivity improved 2.6 times, while the detectivity improved 1.8 times. This research provides a prospect of flexible photodetectors in the near-infrared wavelength., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)